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Renewable energy-based off-grid projects have played a crucial role in Sri Lanka’s universal electrification effort. The paper, in this context, unravels two crucial and quite interrelated aspects of decentralised off-grid electrification in the country: a) it critically analyses the off-grid electricity sector development and assesses its contribution to the universal electrification in the country and; b) it examines the current set of challenges associated with the off-grid electrification in the larger context of massive grid expansion. A mix of quantitative and qualitative research methods is employed as tools of analysis. The paper brings out several policy-relevant findings. Strategic policy interventions coupled with targeted policy goals, robust community-centric management structures, well-designed credit systems, and well-structured capacity-building initiatives are identified as key leveraging points for the success of off-grid electrification projects. The techno-economic analysis of an existing micro-hydro project reveals that there exist opportunities for more productive use of existing capacity. Grid interconnection of off-grid energy projects emerges as a major challenge beset with a whole gamut of technical, legal, regulatory, financial, and social conundrums. Interestingly, the intensity of such challenges differs across ownership types.

Electrification of transport and other energy intensive activities is of growing importance as it provides an underpinning method to reduce carbon emissions. With an increase in reliance on renewable sources of energy and a reduction in the use of more predictable fossil fuels in both stationary and mobile applications, energy storage will play a pivotal role and batteries are currently the most widely adopted and versatile form. Therefore, understanding how batteries work, how they degrade, and how to optimize and manage their operation at large scales is critical to achieving emission reduction targets. The electric vehicle (EV) industry requires a considerable number of batteries even for a single vehicle, sometimes numbering in the thousands if smaller cells are used, and the dynamics and degradation of these systems, as well as large stationary power systems, is not that well understood. As increases in the efficiency of a single battery become diminishing for standard commercially available chemistries, gains made at the system level become more important and can potentially be realised more quickly compared with developing new chemistries. Mathematical models and simulations provide a way to address these challenging questions and can aid the engineer and designers of batteries and battery management systems to provide longer lasting and more efficient energy storage systems.

AbstractThe Green Revolution is often seen as epitomising the dawn of scientific and technological advancement and modernity in the agricultural sector across developing countries, a process that unfolded from the 1940s through to the 1980s. Despite the time that has elapsed, this episode of the past continues to resonate today, and still shapes the institutions and practices of agricultural science and technology. In Brazil, China, and India, narratives of science-led agricultural transformations portray that period in glorifying terms—entailing pressing national imperatives, unprecedented achievements, and heroic individuals or organizations. These “epic narratives” draw on the past to produce meaning and empower the actors that deploy them. Epic narratives are reproduced over time and perpetuate a conviction about the heroic power of science and technology in agricultural development. By crafting history and cultivating a sense of scientific nationalism, exceptionalism, and heritage, these epic narratives sustain power-knowledge relations in agricultural science and technology, which are underpinned by a hegemonic modernization paradigm. Unravelling the processes of assemblage and reproduction of epic narratives helps us make sense of how science and technology actors draw on their subjective representations of the past to assert their position in the field at present. This includes making claims about their credentials to envision and deliver sustainable solutions for agriculture into the future.

Abstract Conventional polymer electrolyte fuel cells (PEFCs) require a means of placing the series of laminar components that make up cells under mechanical compression so as to ensure effective electrical conduction, mass transport and gas-tight operation. This review describes the effect of mechanical compression and dimensional change on the components of PEFCs and reviews the range of methods used to achieve desired stack compression. The case is made for improved understanding of the mechanisms of fuel cell component compression and greater attention to the development of technological approaches for stack compression.

AbstractHalide double perovskites have gained significant attention, owing to their composition of low‐toxicity elements, stability in air, and recent demonstrations of long charge‐carrier lifetimes that can exceed 1 µs. In particular, Cs2AgBiBr6 is the subject of many investigations in photovoltaic devices. However, the efficiencies of solar cells based on this double perovskite are still far from the theoretical efficiency limit of the material. Here, the role of grain size on the optoelectronic properties of Cs2AgBiBr6 thin films is investigated. It is shown through cathodoluminescence measurements that grain boundaries are the dominant nonradiative recombination sites. It also demonstrates through field‐effect transistor and temperature‐dependent transient current measurements that grain boundaries act as the main channels for ion transport. Interestingly, a positive correlation between carrier mobility and temperature is found, which resembles the hopping mechanism often seen in organic semiconductors. These findings explain the discrepancy between the long diffusion lengths >1 µm found in Cs2AgBiBr6 single crystals versus the limited performance achieved in their thin film counterparts. This work shows that mitigating the impact of grain boundaries will be critical for these double perovskite thin films to reach the performance achievable based on their intrinsic single‐crystal properties.

In this study, we report the synthesis and characterization of CdSe nanocrystals (NC's) by facile Hot injection (HI) method. The formation of CdSe NC's was confirmed by x-ray diffraction (XRD), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS). The optical properties were analyzed by UV-visible and photoluminescence (PL) spectroscopy shows an excitonic peak at 600 nm in UV-Vis spectra corresponds to the band gap of ~ 2 eV favorable for optoelectronic device applications. The Photoelectrochemical (PEC) performance of CdSe thin film prepared by spin coating demonstrates a rise of photocurrent density (Jsc = 0.081 µAcm-2) after illumination. The Mott-Schottky (MS) and electrochemical impedance spectroscopy (EIS) measurements were further carried out to understand intrinsic properties namely the type of conductivity, flat band potential, charge carrier density (ND), charge transfer resistance, and recombination lifetime. The n-type conductivity, the charge carrier density of ND = 1.292 x 1016 cm-2, and recombination lifetime of 32.4 µs suggest the ideal behavior of CdSe NC's for device quality photoelectrodes.

<div> <div> <div> <p>An efficient photogeneration of free charge carriers has long been recognized as the paramount challenge in organic photovoltaic (OPV) devices. The low dielectric constant organic semiconductors fall short to reduce strong Coulombic interaction of tightly bound exciton and hence lead to a loss mechanism in OPVs due to charge-carrier recombination. To circumvent this problem, we adopt a strategy to enhance the dielectric constant of organic semiconductors by incorporating tetraethyleneglycol (TEG) side-chains. We report synthesis of three new semiconducting copolymers by combining thiophene substituted diketopyrrolopyrrole (TDPP) monomer with three other monomeric units with varying electron donating strength: benzodithiophene (BBT-3TEG-TDPP), TDPP (TDPP-3TEG-TDPP) and naphthalene diimide (PNDITEG-TDPP). BBT-3TEG-TDPP and PNDITEG-TDPP showed highest dielectric constants (~ 5) at 1MHz frequency suggesting efficient contribution of dipolar polarization from TEG side-chains. To understand the electronic contribution of the polymer backbone and the polarity of TEG side-chains, and the resulting enhancement of the dielectric constant, we further performed first-principles density functional theory calculations. Single-component organic solar cells (OSC) fabricated utilizing these polymers resulted in poor performance which is attributed to the absence of free charge generation. Furthermore, transient absorption spectroscopy studies show low exciton diffusion length as observed in donor-acceptor type conjugated polymers. Our results suggest that, the strategy of enhancing dielectric constant with polar side-chains is not sufficient to reduce Coulombic interaction between hole and electron in OSCs. </p> </div> </div> </div>